package com.video.h264;
public class Base64 {
  private static final byte[] encodingTable = {        
	      (byte) 'A', (byte) 'B', (byte) 'C', (byte) 'D', (byte) 'E',
          (byte) 'F', (byte) 'G', (byte) 'H', (byte) 'I', (byte) 'J',
          (byte) 'K', (byte) 'L', (byte) 'M', (byte) 'N', (byte) 'O',
          (byte) 'P', (byte) 'Q', (byte) 'R', (byte) 'S', (byte) 'T',
          (byte) 'U', (byte) 'V', (byte) 'W', (byte) 'X', (byte) 'Y',
          (byte) 'Z', (byte) 'a', (byte) 'b', (byte) 'c', (byte) 'd',
          (byte) 'e', (byte) 'f', (byte) 'g', (byte) 'h', (byte) 'i',
          (byte) 'j', (byte) 'k', (byte) 'l', (byte) 'm', (byte) 'n',
          (byte) 'o', (byte) 'p', (byte) 'q', (byte) 'r', (byte) 's',
          (byte) 't', (byte) 'u', (byte) 'v', (byte) 'w', (byte) 'x',
          (byte) 'y', (byte) 'z', (byte) '0', (byte) '1', (byte) '2',
          (byte) '3', (byte) '4', (byte) '5', (byte) '6', (byte) '7',
          (byte) '8', (byte) '9', (byte) '+', (byte) '/'
      };
  private static final byte[] decodingTable;
  
  static {
      decodingTable = new byte[128];
      for (int i = 0; i < 128; i++) {
          decodingTable[i] = (byte) -1;
      }
      for (int i = 'A'; i <= 'Z'; i++) {
          decodingTable[i] = (byte) (i - 'A');
      }
      for (int i = 'a'; i <= 'z'; i++) {
          decodingTable[i] = (byte) (i - 'a' + 26);
      }
      for (int i = '0'; i <= '9'; i++) {
          decodingTable[i] = (byte) (i - '0' + 52);
      }
      decodingTable['+'] = 62;
      decodingTable['/'] = 63;
  }
  public static byte[] encode(byte[] data) {
      byte[] bytes;
      int modulus = data.length % 3;
      if (modulus == 0) {
          bytes = new byte[(4 * data.length) / 3];
      } else {
          bytes = new byte[4 * ((data.length / 3) + 1)];
      }
      int dataLength = (data.length - modulus);
      int a1;
      int a2;
      int a3;
      for (int i = 0, j = 0; i < dataLength; i += 3, j += 4) {
          a1 = data[i] & 0xff;
          a2 = data[i + 1] & 0xff;
          a3 = data[i + 2] & 0xff;
          bytes[j] = encodingTable[(a1 >>> 2) & 0x3f];
          bytes[j + 1] = encodingTable[((a1 << 4) | (a2 >>> 4)) & 0x3f];
          bytes[j + 2] = encodingTable[((a2 << 2) | (a3 >>> 6)) & 0x3f];
          bytes[j + 3] = encodingTable[a3 & 0x3f];
      }
      int b1;
      int b2;
      int b3;
      int d1;
      int d2;
      switch (modulus) {
      case 0: /* nothing left to do */
          break;
      case 1:
          d1 = data[data.length - 1] & 0xff;
          b1 = (d1 >>> 2) & 0x3f;
          b2 = (d1 << 4) & 0x3f;
          bytes[bytes.length - 4] = encodingTable[b1];
          bytes[bytes.length - 3] = encodingTable[b2];
          bytes[bytes.length - 2] = (byte) '=';
          bytes[bytes.length - 1] = (byte) '=';
          break;
      case 2:
          d1 = data[data.length - 2] & 0xff;
          d2 = data[data.length - 1] & 0xff;
          b1 = (d1 >>> 2) & 0x3f;
          b2 = ((d1 << 4) | (d2 >>> 4)) & 0x3f;
          b3 = (d2 << 2) & 0x3f;
          bytes[bytes.length - 4] = encodingTable[b1];
          bytes[bytes.length - 3] = encodingTable[b2];
          bytes[bytes.length - 2] = encodingTable[b3];
          bytes[bytes.length - 1] = (byte) '=';
          break;
      }
      return bytes;
  }
  public static byte[] decode(byte[] data) {
      byte[] bytes;
      byte b1;
      byte b2;
      byte b3;
      byte b4;
      data = discardNonBase64Bytes(data);
      if (data[data.length - 2] == '=') {
          bytes = new byte[(((data.length / 4) - 1) * 3) + 1];
      } else if (data[data.length - 1] == '=') {
          bytes = new byte[(((data.length / 4) - 1) * 3) + 2];
      } else {
          bytes = new byte[((data.length / 4) * 3)];
      }
      for (int i = 0, j = 0; i < (data.length - 4); i += 4, j += 3) {
          b1 = decodingTable[data[i]];
          b2 = decodingTable[data[i + 1]];
          b3 = decodingTable[data[i + 2]];
          b4 = decodingTable[data[i + 3]];
          bytes[j] = (byte) ((b1 << 2) | (b2 >> 4));
          bytes[j + 1] = (byte) ((b2 << 4) | (b3 >> 2));
          bytes[j + 2] = (byte) ((b3 << 6) | b4);
      }
      if (data[data.length - 2] == '=') {
          b1 = decodingTable[data[data.length - 4]];
          b2 = decodingTable[data[data.length - 3]];
          bytes[bytes.length - 1] = (byte) ((b1 << 2) | (b2 >> 4));
     } else if (data[data.length - 1] == '=') {
          b1 = decodingTable[data[data.length - 4]];
          b2 = decodingTable[data[data.length - 3]];
          b3 = decodingTable[data[data.length - 2]];
          bytes[bytes.length - 2] = (byte) ((b1 << 2) | (b2 >> 4));
          bytes[bytes.length - 1] = (byte) ((b2 << 4) | (b3 >> 2));
      } else {
          b1 = decodingTable[data[data.length - 4]];
          b2 = decodingTable[data[data.length - 3]];
          b3 = decodingTable[data[data.length - 2]];
          b4 = decodingTable[data[data.length - 1]];
          bytes[bytes.length - 3] = (byte) ((b1 << 2) | (b2 >> 4));
          bytes[bytes.length - 2] = (byte) ((b2 << 4) | (b3 >> 2));
          bytes[bytes.length - 1] = (byte) ((b3 << 6) | b4);
      }
      return bytes;
  }
  public static byte[] decode(String data) {
      byte[] bytes;
      byte b1;
      byte b2;
      byte b3;
      byte b4;
      data = discardNonBase64Chars(data);
      if (data.charAt(data.length() - 2) == '=') {
          bytes = new byte[(((data.length() / 4) - 1) * 3) + 1];
      } else if (data.charAt(data.length() - 1) == '=') {
          bytes = new byte[(((data.length() / 4) - 1) * 3) + 2];
      } else {
          bytes = new byte[((data.length() / 4) * 3)];
      }
      for (int i = 0, j = 0; i < (data.length() - 4); i += 4, j += 3) {
          b1 = decodingTable[data.charAt(i)];
          b2 = decodingTable[data.charAt(i + 1)];
          b3 = decodingTable[data.charAt(i + 2)];
          b4 = decodingTable[data.charAt(i + 3)];
          bytes[j] = (byte) ((b1 << 2) | (b2 >> 4));
          bytes[j + 1] = (byte) ((b2 << 4) | (b3 >> 2));
          bytes[j + 2] = (byte) ((b3 << 6) | b4);
      }
      if (data.charAt(data.length() - 2) == '=') {
          b1 = decodingTable[data.charAt(data.length() - 4)];
          b2 = decodingTable[data.charAt(data.length() - 3)];
          bytes[bytes.length - 1] = (byte) ((b1 << 2) | (b2 >> 4));
      } else if (data.charAt(data.length() - 1) == '=') {
          b1 = decodingTable[data.charAt(data.length() - 4)];
          b2 = decodingTable[data.charAt(data.length() - 3)];
          b3 = decodingTable[data.charAt(data.length() - 2)];
          bytes[bytes.length - 2] = (byte) ((b1 << 2) | (b2 >> 4));
          bytes[bytes.length - 1] = (byte) ((b2 << 4) | (b3 >> 2));
      } else {
          b1 = decodingTable[data.charAt(data.length() - 4)];
          b2 = decodingTable[data.charAt(data.length() - 3)];
          b3 = decodingTable[data.charAt(data.length() - 2)];
          b4 = decodingTable[data.charAt(data.length() - 1)];
          bytes[bytes.length - 3] = (byte) ((b1 << 2) | (b2 >> 4));
          bytes[bytes.length - 2] = (byte) ((b2 << 4) | (b3 >> 2));
          bytes[bytes.length - 1] = (byte) ((b3 << 6) | b4);
      }
      return bytes;
  }
  private static byte[] discardNonBase64Bytes(byte[] data) {
      byte[] temp = new byte[data.length];
      int bytesCopied = 0;
      for (int i = 0; i < data.length; i++) {
          if (isValidBase64Byte(data[i])) {
              temp[bytesCopied++] = data[i];
          }
      }
      byte[] newData = new byte[bytesCopied];
      System.arraycopy(temp, 0, newData, 0, bytesCopied);
      return newData;
  }
  private static String discardNonBase64Chars(String data) {
      StringBuffer sb = new StringBuffer();
      int length = data.length();
      for (int i = 0; i < length; i++) {
          if (isValidBase64Byte((byte) (data.charAt(i)))) {
              sb.append(data.charAt(i));
          }
      }
      return sb.toString();
  }
  private static boolean isValidBase64Byte(byte b) {
      if (b == '=') {
          return true;
      } else if ((b < 0) || (b >= 128)) {
          return false;
      } else if (decodingTable[b] == -1) {
          return false;
      }
      return true;
      };
}